The present invention relates to a hard disk drive, and more particularly, to a hard disk drive with a self-servowriting capability.
A hard disk drive is widely used as a memory device in a computer, and is generally much lower in price than other memory devices. This is largely due to the fact that the hard disk drive can be constructed from inexpensive components. Accordingly, the hard disk drive can be manufactured at a relatively low cost. A servowriter is an essential device for the hard disk drive, and is used for writing servo information in servo sectors of a recording disk.
A servo sector generally includes a read/write recovery and auto gain control AGC sector for regularly maintaining the time required for a head to change from an operation for writing data to an operation for reading servo information, and for defining the size of a position signal read through the head on an entire disk area. A servo address mark SAM sector provides an area in which a standard pattern for servotiming is written. An index IDX sector is an area for providing disk rotation information. A gray code sector includes address information regarding servo sectors, and head and cylinder numbers. A servo burst sector is provided for controlling on-track positioning of the head.
The servowriter is the highest-priced device of all the devices used in constructing a hard disk drive. Recently, the function of the servowriter has been emphasized in order to increase the writing density and provide the hard disk with a large data storage capacity. The cost of the servowriter, together with the time required for servowriting, have become key elements in determining the cost efficiency of the manufacturing process. A voice coil motor VCM generally used in a hard disk drive system employs an acceleration control method, and therefore, it cannot be maintained in a regular position without the use of a servo-pattern written on the disk surface. Accordingly, in order to write the servo-pattern for controlling the position of the head, a high-priced position control system is required.
Several prior art references discuss the subject of servowriting in a disk recording apparatus. One reference, U.S. Pat. No. 5,162,955 entitled Apparatus For Writing Servo Information Onto A Magnetic Disk issued to Burdenko, discloses an apparatus that seeks to improve the tracking of a head actuator that writes servo information onto a disk surface. In Burdenko '955, a feedback circuit connected between a tracking element and an actuator drive monitors the position of the tracking element as a measure of the radial position of the head for controlling the action of the drive to move the head to selected radial positions within a desired degree of radial accuracy. While conventional art, such as Burdenko '955, provides advantages in its own right, I believe that an improved technique for servowriting in a disk recording apparatus can be contemplated.